Traveling casing systems for mine workings



Oct. 20, 1970 H. RIESCHEL 3,534,560

TRAVELING CASING SYSTEMS FOR MINE WORKINGS Filed Jan. 31. 1968 '2 Shts-Sheetl 1970 H. RIESCHEL TRAVELING CASING SYSTEMS FOR MINE WORKINGS Filed Jan. 51, 1968 2 Sheets-sheaf 2 FIG. 2

bu s 1 1 la 1 7 g/migllm US. Cl. 61-45 1 Claim ABSTRACT OF THE DISCLOSURE This invention relates to a travelling casing system for a mine working of the kind including hydraulically operated casing frames or trusses, the pit props of which are articulated at least to the floor rails or the casing head and can be placed in a predetermined position using a control system for regulating aligning cylinders and which determines the deviation of the pit props from their theoretical or nominally correct positions and operates the aligning cylinders accordingly, and is characterised by the fact that the pit props of each frame are connected to one another through links incorporating ball joints of adjustable tightness.

BACKGROUND OF THE INVENTION A travelling casing system of the kind referred to does not yet form part of the state of the art. It possesses one or more controllers, for which the controlled quantity is the inclination of the pit prop axis relative to a nominal line. These controllers can automatically effect correction of the attitude of the pit props in order to bring their axes back into a theoretical position, the theoretical position generally speaking being perpendicular to the lie of the working. The advantage of this is that the pit props are able to provide maximum support and safety, independently of any disturbing factors which may be at work.

PRIOR ART However, it is well known to employ leaf springs to return the pit props to their theoretical positions. Usingaligning cylinders overcomes the disadvantage associated with the use of leaf springs, namely that the correcting forces which they can develop are limited.

Nevertheless, hitherto it has not been possible, with travelling casing systems of the kind referred to hereinbefore, totally to dispense with spring elements of this kind, since, with the pit props in the unloaded condition, the aligning cylinders exert no force on the pit props, or at any rate only an inadequate force, when mounted on neighbouring casing frames and in particular on the casing heads thereof. Thus, if all the pit props of a casing system are to be collapsed, steel springs must be provided to prevent the pit props toppling when the load is removed.

If an analysis is made of the costs associated with casing frames or trusses of this sort, which are equipped with steel spring elements, then it is quickly apparent that depending upon the particular design, half or more of the overall cost is attributable to the spring elements. The introduction of travelling casing techniques, which is part and parcel of the effort towards greater rationalisation in mining operations, demands that there should be a reduction in the cost of casing and therefore that the spring elements should be discarded, in particular for the additional reason that the outlay they entail rises progressively as the width or thickness of the working or lode increases and the dip steepens.

nited States atent ice SUMMARY OF THE INVENTION This problem is overcome, in accordance with the invention, by virtue of the fact that the pit props of the frame are attached to one another through links, provided at the points of attachment to the props with ball joints which, by adjustment of their frictional tightness, are set to be overcome by a predetermined minimum force which is smaller than the pivoting forces exerted by the aligning cylinders, but larger than the pivoting forces acting upon the props when the latter are unloaded.

With implementation of these features, the leaf springs hitherto employed can be dispensed with. Thus, with the pit props in the unloaded condition, the joints are sufliciently stiff to prevent the casing system from collapsing. For example, the pivoting forces acting upon the pit props when they travel beneath a ledge in the roof of the working, are too small to produce any movement at the joints.

On the other hand, these joints can be moved by the aligning cylinders, and also, of course, by the extraneous forces operative when the pit props are in the loaded condition, so that risk of overloading of the pit props is prevented.

In accordance with a further feature of the invention, the forces required to move the joints are preset by adjustment of the joint friction. In this case, the joints are designed as friction joints.

From the practical point of view, this kind of joint can be achieved by giving the ball joint an internal part attached to the pit pro which consists of a spherical segment or a sphere flattened at its two poles and penetrated by the body of the pit prop in a direction perpendicular to the flattened polar regions, and an external part consisting of a multipiece, in particular a two-piece, ball seating the individual components of which are loaded into contact with the internal part of the joint.

A joint of this kind can for example, in accordance with a further feature of the invention, be adjusted to produce the requisite friction forces and therefore the requisite deflection force, by providing tensioning screws which embrace the internal part of the joint and pass through the spherical seating, possibly being associated with tensioning springs as well. Simply by rotating nuts, which cooperate with these screws or bolts, the contact pressure between the external and internal parts of the joint can be increased or reduced and therefore also the friction couple of the joint.

The casing system with which the invention is concerned may be one using pit props which are freely articulated to the casing heads and, where these are provided, to the floor rails and/or baseplates.

DESCRIPTION OF DRAWINGS Further feautres of the invention will be apparent from the following description of a preferred example, referring to the accompanying drawings, in which:

FIG. 1 schematically illustrates in perspective a hydraulic casing system in accordance with the invention, omitting in essential details;

FIG. 2 is a side elevation of a hydraulic casing frame in accordance with the invention; and

FIG. 3 shows, partially in section and partly cut away, a joint forming part of said casing frame.

In FIG. 1 is illustrated a hydraulic casing system consisting of two casing frames 2 and 3 linked together to form a truss. Since the frames 2 and 3 forming the truss are identical in design, it will suflice, in general, to describe only one of them in detail.

The frames each consist of a casing head 4 and two pit props 5. As FIG. 2 shows, each pit prop is articulated at the point 6 to a baseplate 7, having an upcurved toe 7a to allow it to slide over irregularities in. the sill of the working. The pit props are also articulatingly connected to the interior of the casing head 4.

Each frame is equipped with a controller, details of which have not been illustrated. The controlled quantity associated with this controller is the attitude or orientation of the pit prop axis, the arrows 9 and 10 shown in FIG. 1 indicating deviations of the controlled quantity from a theoretical or nominal position, for example the position of the pit prop axis when the pit prop is perpendicular to the lie of the working. The controller is provided with one or more servo elements in the form of conventional aligning cylinders, which have not been shown, and these can exert forces in the neighbourhood of the casing head, which are directed transversely in the plane of the casing frame, as indicated by the arrows P and P in order to restore the pit props to the theoretical attitude should the controlled quantity indicate deviation therefrom.

As FIG. 2 indicates, the pit props of each frame are connected with one another through rigid links 12. The ends of the links are connected to the associated pit props 5 through pivotal joints 13. The details of these pivotal joints will be apparent from the illustration of FIG. 3, in association with FIG. 2.

In the example in question, the joints are friction joints. Each joint has an internal part 14 in the form of a spherical segment or, as in the particular example, in the form of a sphere 15 flattened at two polar regions 15a, 15b. The axis of the associated pit prop 5 extends perpendicularly to the flattened polar regions 15a, 15b. In practice, the sphere 15, flattened at its poles, is slid over the outer case of the pit prop, after the baseplate 7 has been removed, and axially secured there in a suitable manner.

The joint also has an external part 16. This consists, as FIG. 3 clearly shows, of a split spherical seating made up of the two halves 17 and 18, which latter are adapted to be tensioned together by identical bolts 19 and 20 thus clamping between them the internal part 14 of the joint. These tensioning screws, in the particular example chosen, embrace between them the inner half 14 of the joint and thus also the pit prop 5. Their screwed ends 21 have spring tensioning, for example provided by stacks of spring washers slipped over them, and are provided with respective nuts 23 which bear against the spring washers through a suitable plain washer.

It will be clear that by screwing up the nuts 23 with varying degrees of tightness, the friction at the joint can be modified and set to a specific value which requires a predetermined minimum force to overcome it.

The friction of the joint is adjusted so that this predetermined force is smaller than the forces P P exerted by the cylinders acting as the servo elements of the controller. This means that the joints can operate under the action of the said servo elements and that they can also operate in circumstances where the earth pressure is so heavy that the pit props 5 have to yield in order to avoid permanent distortion or damage.

On the other hand, the said predetermined force corresponding to the friction of each joint 13 is greater than the deviating forces necessitating the provision'of the controller and active when the pit props are in the unloaded condition, i.e., greater than the sum of the forces which tend to deflect the axes of the collapsed pit props in the directions indicated by the arrows 9 and 10. Accordingly, the joints 13 behave as rigid connections when the pit props 5 are unloaded, so that the casing system is prevented from toppling.

In the example illustrated, it is not only the pit props of the frame which are connected with one another through links 12, but in addition, extra links 33 are connected between the frames, these likewise being attached to the said joints. The provision of still further linking elements 34 between the casing heads is also a matter of choice.

The main advantage of the casing system hereinbefore described resides in the fact that it requires no springs or similar elements in order to retain its stability when the pit props are unloaded. These elements are instead replaced by the joints 13 on the links 12, the latter links only having to resist very small forces with the consequence that they can have a light simple design and do not therefore make the casing system more expensive.

What is claimed is:

1. In a travelling casing system in a mine working, comprising hydraulically operated casing units incorporating pit props having articulated mountings, and a control system incorporating aligning cylinders for determining deviations in the orientations of the pit props relative to their nominally required positions and for operating the aligning cylinders to rectify said deviations, the improvement constituted by the combination of links connecting together the individual pit props of each casing unit, ball joints attaching each said link to its respective pit props, each ball joint consisting of an internal ball shaped part having two flattened polar regions and a bore perpendicular to said regions receiving the pit prop shaft to connect said internal part to the pit prop, and an external part constituted by at least two components defining a spherical seating, and adjusting means comprising tensioning screw means passing through the components of the said external part with the internal part located between them for variably loading the components of the said external part into contact with the said internal part, whereby the frictional tightness of the ball joints may be adjusted to a level such that the friction will be overcome by a predetermined minimum force less than the pivoting forces exerted by the aligning cylinders, but larger than the pivoting forces acting on the pit props when the latter are unloaded.

References Cited UNITED STATES PATENTS 2,652,221 9/1953 Kampa 248278 1,909,917 5/1933 Hover 287--89 3,115,754 12/1963 Joseph 61-45 3,309,054 3/ 1967 Davis-Ratclitfe 61-45 FOREIGN PATENTS 707,594 4/1931 France.

JACOB SHAPIRO, Primary Examiner U.S. Cl. X.R. 285--261; 287-88, 89 

